1. Field of the Invention
The present invention relates to a power amplifier circuit, and particularly to an improved power amplifier circuit in which the power consumption can be reduced by the adjustment of adjusting means.
2. Description of the Prior Art
In a prior art power amplifier of, for example, a radio receiver including push-pull-connected power amplifying transistors, the primary side of an output transformer is adjusted in accordance with the volume control of the radio receiver to vary its output impedance so that the efficiency of the power amplifier may be adjusted to reduce its power consumption. In this case, the biasing voltage of the power amplifying transistors is always substantially constant, so that the power consumption relating to this biasing voltage can not be greatly reduced.
Further, because of employing the push-pull-connected power amplifying transistors, when the primary side of the output transformer is adjusted, both of the transistors must be also adjusted in a similar manner, so that particular design and control are required to make the circuit complicated.